I took out my revolver and laid it on the corner of the table.
Holmes had brought up a long thin cane, and this he placed upon the bed beside him. By it he laid the box of matches and the stump of a candle. Then he turned down the lamp, and we were left in darkness.
How shall I ever forget that dreadful vigil? I could not hear a sound, not even the drawing of a breath, and yet I knew that my companion sat open-eyed, within a few feet of me, in the same state of nervous tension in which I was myself. The shutters cut off the least ray of light, and we waited in absolute darkness.
From outside came the occasional cry of a night-bird, and once at our very window a long drawn catlike whine, which told us that the cheetah was indeed at liberty. Far away we could hear the deep tones of the parish clock, which boomed out every quarter of an hour. How long they seemed, those quarters! Twelve struck, and one and two and three, and still we sat waiting silently for whatever might befall.
Suddenly there was the momentary gleam of a light up in the direction of the ventilator, which vanished immediately, but was succeeded by a strong smell of burning oil and heated metal.
Someone in the next room had lit a dark-lantern. I heard a gentle sound of movement, and then all was silent once more, though the smell grew stronger. For half an hour I sat with straining ears.
Then suddenly another sound became audible--a very gentle, soothing sound, like that of a small jet of steam escaping continually from a kettle. The instant that we heard it, Holmes sprang from the bed, struck a match, and lashed furiously with his cane at the bell-pull.
"You see it, Watson?" he yelled. "You see it?"
But I saw nothing. At the moment when Holmes struck the light I heard a low, clear whistle, but the sudden glare flashing into my weary eyes made it impossible for me to tell what it was at which my friend lashed so savagely. I could, however, see that his face was deadly pale and filled with horror and loathing. He had ceased to strike and was gazing up at the ventilator when suddenly there broke from the silence of the night the most horrible cry to which I have ever listened. It swelled up louder and louder, a hoarse yell of pain and fear and anger all mingled in the one dreadful shriek. They say that away down in the village, and even in the distant parsonage, that cry raised the sleepers from their beds. It struck cold to our hearts, and I stood gazing at Holmes, and he at me, until the last echoes of it had died away into the silence from which it rose.